The unmanned planes look north toward the long, lightly defended and admittedly porous Canada-U.S. border – the best route many Americans believe for jihadists seeking to attack the United States to sneak across.

Like their missile-carrying military cousins prowling Pakistan's skies targeting al-Qaeda suspects, the unarmed Predator aircraft that have patrolled the 49th parallel since 2009 are high-tech, sophisticated and little understood. And they are part of the same diffuse and determined effort the United States is making to secure its borders and defend itself.

"We're here to protect the nation from bad people doing bad things," says John Priddy, U.S. National Air Security Operations director for the Customs and Border Protection's Office of Air and Marine. He heads the Predator operation guarding American's northern airspace.

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"This is the equivalent of the Cold War in terms of a new type of vigilance," says Mr. Priddy, who has flown everything from Boeing 747 cargo jets to Apache helicopters.

No one says "terrorism," but no one has to. On Mr. Priddy's office wall, there's a fading photograph of the burned-out tail of a Pam Am Boeing 747 after it was blown up by Palestinian hijackers in Cairo in 1970. The pilot of that flight was his father, also named John Priddy.

Now, with a team of a few dozen, this John Priddy is running a futuristic – and slightly unsettling – surveillance system, a test program with only two planes operating in a relatively small zone that could grow into a fleet of unmanned aircraft watching the border day and night in all weather.

In an effort to demystify the unmanned aerial surveillance along 1,500 kilometres of the Canada-U.S. border, the U.S. Department of Homeland Security invited The Globe and Mail to visit its National Air Security Operations base in Grand Forks, N.D. There, a pair of Predators are prowling America's northern frontier, providing protection without, the department insists, infringing on the privacy of Canadians on the other side of the border.

Eyes in the skies

On the ground, the Predator-B looks like a giant, ungainly carbon-fibre insect with a flattened hammerhead where a cockpit would usually be found. It sports a spindly undercarriage, long elegant wings and a propeller behind a V-shaped tail. Once aloft, it disappears, the sound of its single powerful engine fading even faster than the blue-grey fuselage melds with the sky. Within seconds it is gone, yet its powerful cameras and radar can peer down, beaming detailed surveillance images taken from many kilometres away.

To illustrate just how detailed and undetectable the Predators can be, Mr. Priddy described how staff watched a car stop briefly on one of the many rural roads that run parallel to the border. A handful of men got out, oblivious to the Predator circling perhaps five kilometres up. These men, like others before them, were Somalis, heading north, trying to sneak into Canada, Mr. Priddy said. The RCMP was alerted.

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The full range of the planes' capabilities is still being explored. Last spring, for instance, during the devastating floods along the Red and Souris rivers, the Predators provided real-time video of water-ravaged areas, and flew all the way up the Mississippi. Ice buildup threatening bridges showed clearly on the radar.

It feels a lot like Big Brother is watching. The data – video, radar and thermal imagery – streams back to control rooms and can be watched live or stored for later analysis. It can be delivered simultaneously to border patrol, police and other ground units, or put on the open Internet in the case of emergencies.

But even with flights that can last for 10 hours, the Predators provide only an occasional presence over any one spot. It's the unpredictability of where one could be, and the near impossibility to detect it even overhead, that provide its powerful deterrent value. That's one of the reasons DHS wants it widely known that Predators are patrolling the borders.

'Don't call them drones'

Nothing irks the pilots who fly Predators and other unmanned aircraft more than having them dubbed "drones," although the ubiquity of the term seems certain to prevail. "Drones" conjure up images of a mostly autonomous existence and these are anything but. The pilot just doesn't sit inside.

"Call them UAVs – for unmanned aerial vehicle – or just Predators," a pilot at Grand Forks pleads. Teams of two operate the Predators, with one piloting the aircraft by looking through its forward mounted camera. The other, a sensor operator, controls the turret beneath the nose that can focus camera or radar on objects or people many kilometres away and remain "locked on" even as the aircraft circles. Long flights can be flown by shifts of pilots from any properly equipped control centre with a satellite link.

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Almost all the pilots have military backgrounds and long experience flying in very difficult conditions, but say that piloting the Predator is very demanding, made all the harder because the pilots have a very narrow field of vision and have none of the "seat of the pants" feelings of gravity and momentum that regular pilots rely upon. Imagine riding a bicycle while peering through opera glasses while sitting in a closet.

Old base, new war

No active military units remain at this vast air base outside Grand Forks, only the ghosts of another war: a mammoth B-52 Stratofortress bomber and a phallic Minuteman ballistic missile guard the gate, proclaiming "Warriors of the North."

The Predators are the only aircraft currently stationed here. The two planes, one at a time, patrol from Muskeg Bay, in the Lake of the Woods area on the Ontario-Minnesota border, to roughly 1,500 kilometres west beyond Spokane, Wash., and from the 49th parallel to 160 kilometres south. That's 246,000 square kilometres to roam, or roughly the airspace over Britain.

In the busy operations centre, there is a keen awareness that Canadians – who throng Grand Forks on weekends for everything from hockey tournaments to shopping sprees – regard the Predators with a mix of trepidation and resentment. "We work closely with our counterparts on the Canadian side," Mr. Priddy says, aware of the need to reassure Canadians that unmanned planes patrolling the border are meant to protect the United States, not invade Canadian privacy.

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